Brushes have been used for many years to polish, clean and abrade a wide variety of substrates. These brush products typically have a plurality of bristles that contact the substrate. Abrasive particles can be added to bristles to increase their abrasiveness.
U.S. Pat. No. 3,233,272, "Rotary Brush," (Pambello), discloses brushes, particularly rotary brushes of the annularly or spirally arranged brush strip type which are primarily adapted for heavy duty such as brushing paved streets, sidewalks, concrete flooring and the like. In one embodiment, the rotary brush of Pambello comprises a rotatable structure, a brushing element formed of a unitary strip of yieldable plastic material annularly arranged on the structure, the strip having a lengthwise extending base and having vane means extending outwardly from the base and formed with a tip at the outer end thereof. The brush strip of Pambello may be formed of plastic materials by molding or extruding and cutting operations.
U.S. Pat. No. 5,233,794, "Rotary Tool Made of Inorganic Fiber-Reinforced Plastic," (Kikutani et al.), discloses a rotary tool 5 having a rotating tip formed integrally with a shaft 3. The rotary tool is formed of a thermosetting resin containing inorganic long fibers with a high degree of hardness as an abrasive means in an amount from 50% to 81% by volume. The long inorganic fibers can have a diameter in the range of 3 .mu.m to 30 .mu.m. In one of the embodiments of Kikuluani et al., the rotating tip is formed as a column or cylinder with elements which correspond to the bristle of a brush extending from the tip.
It is known to form various types of abrasive filaments from thermoplastic elastomers. U.S. Pat. No. 5,427,595 (Pihl) discloses an extruded abrasive filament including a first elongate filament component having a continuous surface throughout its length and including a first hardened organic polymeric and a second elongate filament component coterminous with the first elongate filament component, including a second hardened organic polymeric material in melt fusion adherent contact with the first elongate filament component along the continuous surface. The second hardened organic polymeric material can be the same or different than the first hardened organic polymeric material. At least one of the first and second hardened organic polymeric materials includes a thermoplastic elastomer having abrasive particles adhered therein. Also disclosed is an abrasive article comprised of at least one abrasive filament mounted to a substrate such as a hub adapted to be rotated at a high rate of revolution.
U.S. Pat. No 5,460,883 (Barber) discloses a composite abrasive filament which includes at least one preformed core at least partially coated with a thermoplastic elastomer having abrasive particles dispersed and adhered therein, the thermoplastic elastomer and abrasive particles together comprising a hardened composition. The composite abrasive filament has a hardened composition over at least a portion, preferably over the entire surface of at least one preformed core. The preformed core is formed in a step separate from and prior to one or more coating steps, one of which coats the preformed core with abrasive-filled thermoplastic elastomer.
U.S. Pat. Nos. 5,174,795 and 5,232,470 (Wiand) teach a planar abrasive article comprising a sheet portion with a plurality of protrusions extending therefrom. Abrasive particles are homogeneously dispersed throughout the moldable material comprising the article. Wiand teaches one embodiment having short protrusions extending 1.6 mm (0.063 in) from the backing and having a 3.2 mm (0.125 in) diameter, and another embodiment having short protrusions extending 1.3-1.5 mm (0.05-0.06 in) from the backing and having a 1.3 mm (0.05 in) diameter.
G.B. Patent Application No. 2.043,501, (Dawkins) discloses an abrasive article for polishing ophthalmic workpieces. The abrasive article is made by injection molding a mixture of abrasive grains and a thermoplastic binder to form an abrasive article comprising a flexible backing having a plurality of upstanding projections, the ends of which act as operative abrading surfaces.
It is known to integrally mold bristles with the backing of a brush. U.S Pat. No. 5,679.067 issued Oct 21, 1997, discloses a molded abrasive brush having a backing with a plurality of bristles extending therefrom. The backing and bristles are preferably integrally molded. The brush is molded from a moldable polymer such a thermoset polymer, thermoplastic polymer, or thermoplastic elastomer. The moldable polymer includes a plurality of organic or inorganic abrasive particles interspersed throughout at least the bristles, and can be interspersed throughout the brush. The moldable brush can include an attaching means molded integrally with the backing. Johnson et al. discloses that the bristles may have any cross sectional area, including but not limited to, circular, star, half moon, quarter moon, oval, rectangular, square, triangular, diamond or polygonal. In one preferred embodiment, the bristles of Johnson et al. comprise a constant circular cross section along the length of the bristle. In other preferred embodiments of Johnson et al., the bristles have a non-constant or variable cross section along all or a portion of the length of the bristle. Similar brushes are also disclosed in WIPO International Patent Application Publication No. WO 96/33638. U.S. patent application Ser. No. 08/782,782, Holmes et al., filed Jan. 13, 1997, discloses similar brushes which additionally include knobs configured to engage with holes in a retainer nut.
ROLOC.TM. Bristle Brushes are commercially available from Minnesota Mining and Manufacturing Company, St. Paul, Minn. Such brushes are molded abrasive brushes having a backing with a plurality of bristles extending therefrom. The backing and bristles are integrally molded. The brush is molded from a thermoplastic elastomer and includes a plurality of abrasive particles interspersed throughout brush. The bristles have a circular cross section along the length of the bristle, and are tapered to be wider at the base than at the tip.